Part way through the process, a plastic lug had to be hammered in to a
small hole. You can see it in this picture.

If you just went ahead and bashed this in, chances are you'd end up
with a deformed bit of plastic. It's always best to lay something suitable
over the lug, and then hammer that, rather than hammering the lug directly.

Of course, the question is, what do you use?

After looking around, we finally settled on a suitable piece of padding.

Of course, whenever you do work like this, it is very important to make
sure that you're hammering squarely down on the target, so that the force
is used to drive the lug into the wood, and not off to one side.